The present invention relates to a variable-pitch blade made of composite material for a helicopter rotor and to the method for manufacturing it. The invention applies especially, although not exclusively, to variable-pitch blades intended to equip helicopter tail rotors.
Composite materials offer an attractive solution to the problem of producing helicopter blades with low mass. The technique most commonly employed relies on the use of fabrics which are preimpregnated with a thermosetting resin. This allows various constituent elements of the blade to be assembled and the assembly to be secured together by heating in a mould under pressure (see FR-A-2,616,409 for example or the corresponding U.S. Pat. Nos. 4,892,462 and 4,990,205). This technique provides satisfactory blades, but with a relatively high manufacturing cost, due mainly to the difficulty in mass-producing reliable quality blades, and to the fact that various elements still have to be added to the blade once it is removed from the mould.
An object of the present invention is to propose a method for manufacturing a blade made of composite material making it possible to obtain a quality blade in a reliable and economical manner.